Merge pull request #1472 from ravening/command

#1324 Use interfaces in command pattern

command/README.md

@@ -75,19 +75,18 @@ public class Wizard {
 Next we present the spell hierarchy.
 
 ```java
-public abstract class Command {
+public interface Command {
 
-  public abstract void execute(Target target);
+  void execute(Target target);
 
-  public abstract void undo();
+  void undo();
 
-  public abstract void redo();
+  void redo();
 
-  @Override
-  public abstract String toString();
+  String toString();
 }
 
-public class InvisibilitySpell extends Command {
+public class InvisibilitySpell implements Command {
 
   private Target target;
 
@@ -117,7 +116,7 @@ public class InvisibilitySpell extends Command {
   }
 }
 
-public class ShrinkSpell extends Command {
+public class ShrinkSpell implements Command {
 
   private Size oldSize;
   private Target target;

command/etc/command.urm.puml

@@ -4,7 +4,7 @@ package com.iluwatar.command {
     + App()
     + main(args : String[]) {static}
   }
-  abstract class Command {
+  interface Command {
     + Command()
     + execute(Target) {abstract}
     + redo() {abstract}
@@ -77,7 +77,7 @@ ShrinkSpell -->  "-oldSize" Size
 InvisibilitySpell -->  "-target" Target
 ShrinkSpell -->  "-target" Target
 Target -->  "-visibility" Visibility
-Goblin --|> Target 
-InvisibilitySpell --|> Command 
-ShrinkSpell --|> Command 
-@enduml
\ No newline at end of file
+Goblin --|> Target
+InvisibilitySpell ..|> Command
+ShrinkSpell ..|> Command
+@enduml

command/src/main/java/com/iluwatar/command/Command.java

@@ -26,15 +26,12 @@ package com.iluwatar.command;
 /**
  * Interface for Commands.
  */
-public abstract class Command {
+public interface Command {
+  void execute(Target target);
 
-  public abstract void execute(Target target);
+  void undo();
 
-  public abstract void undo();
-
-  public abstract void redo();
-
-  @Override
-  public abstract String toString();
+  void redo();
 
+  String toString();
 }

command/src/main/java/com/iluwatar/command/InvisibilitySpell.java

@@ -26,7 +26,7 @@ package com.iluwatar.command;
 /**
  * InvisibilitySpell is a concrete command.
  */
-public class InvisibilitySpell extends Command {
+public class InvisibilitySpell implements Command {
 
   private Target target;
 

command/src/main/java/com/iluwatar/command/ShrinkSpell.java

@@ -26,7 +26,7 @@ package com.iluwatar.command;
 /**
  * ShrinkSpell is a concrete command.
  */
-public class ShrinkSpell extends Command {
+public class ShrinkSpell implements Command {
 
   private Size oldSize;
   private Target target;